According to Iran's Islamic Republic News Agency, the Iranian military has shot down a RQ-170 Sentinel, which is the U.S. Air Force's stealth drone

Iran announced that it has shot down a U.S. stealth drone within its borders, but the U.S. believes the craft could be an unmanned reconnaissance plane instead.

According to Iran's Islamic Republic News Agency, the Iranian military has shot down a RQ-170 Sentinel, which is the U.S. Air Force's stealth drone.

The RQ-170 Sentinel, also known as "Beast of Kandahar," is an unmanned drone that was developed by Lockheed Martin and based in Afghanistan. It has an isosceles trapezoid-shaped inlet, which is a common shape for stealthy aircraft. Its main purpose is to carry out secret missions into Pakistan and it is believed that the drone also secretly spies on Iranian military sites. Initially, the U.S. Air Force denied the existence of the drone in order to keep it classified, and it is still unknown how many of them exist.

Iran announced that it had shot down and captured the RQ-170 on Sunday after it had violated the country's airspace near the eastern border, but the U.S. and the North Atlantic Treaty Organization (NATO) are not so sure. U.S. officials say there is no evidence that the drone had been shot down.

NATO noted that Iran may have instead found an unmanned reconnaissance plane, which was lost while flying over western Afghanistan last week.

"The operators of the UAV lost control of the aircraft and had been working to determine its status," said NATO's International Security Assistance Force.

The U.S.' doubt regarding Iran's possession of the RQ-170 stems from Iran's previous claims of shooting down drone's with no evidence. Back in January, Tehran said its military shot down drones in the Gulf. Later in July, it claimed to shoot down a drone near Qom. Tehran could not produce evidence of either incident.

It is currently unknown what kind of U.S. drone has disappeared, but if Iran's military really does have the RQ-170 in its possession, it could be problematic for the U.S. since the drone contains its powerful "technological secrets" such as high-tech cameras, listening systems, and coatings/materials that make it challenging to identify.

According to The Wall Street Journal, Tehran may not be able to copy the technology itself, but it could sell the drone to Russia or China for that purpose.